Side impact reinforcement

ABSTRACT

An expansible reinforcer for reinforcing a hollow structural member of an automobile, aircraft, boat, etc. is provided. The reinforcer is flexible/bendable and comprises a synthetic, resin-based expansible reinforcing material secured thereto. In a preferred embodiment, the reinforcer comprises a plurality of supports pivotally connected to one another in a train-like arrangement. The reinforcing material is formed of a thermally expansible composition which preferably has an expansion temperature similar to the temperatures achieved in specific stages of a particular manufacturing process (e.g., such as the temperature at which the paint bake or powder bake stage is carried out in the automobile manufacturing process). The inventive reinforcer is capable of being fed into the opening of a tight cavity on a structural member so as to provide uniform reinforcement of the structural member.

This application is a divisional of U.S. patent application Ser. No.09/663,566, filed Sep. 15, 2000, incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is broadly directed towards a reinforcer andmethod of using the reinforcer to reinforce hollow structural memberssuch as those commonly found in vehicles. More particularly, thereinforcer comprises a support having an expansible, synthetic resinreinforcing material attached thereto, wherein the reinforcer issufficiently flexible or bendable to allow it to negotiate nonlinear orirregular shaped cavities.

2. Description of the Prior Art

During the design and development of automobiles, trucks, aircraft,watercraft, etc., much of the body structure includes hollow cavities,rails, or frame sections. Many times, the structural integrity of thebody is improved through increasing the stiffness in localized criticalareas. Increased stiffness in these areas generally results in reducedvibration, noise, and/or fatigue propagation. Additional stiffness inthese areas has also provided energy management during crash or impactsituations.

Many attempts have been made to reinforce these cavities. One suchmethod involves introducing self-sustaining, reinforcing products intothe cavity, either with or without a support or carrier structure.However, these methods generally result in the addition of excess weightto the structural member which is undesirable in most instances.

Attempts have also been made to utilize reinforcing products which arelighter in weight or which do not use a support structure, but theseattempts usually involve products which lack the necessary strength forproperly reinforcing the structural member. Many times the foamableportions of these products do not sufficiently expand upon heating dueto the fact that the center of the material is not being properly heatedduring the activation process. That is, the size of the foam product issufficiently thick that the core of the product is exposed to minimalheat, thus preventing the core from fully expanding. This can lead to aninadequately reinforced structural member.

Furthermore, many of the structural members that need reinforcement havecavities that are irregular in shape or narrow in size, thus making themdifficult, if not impossible, to sufficiently position currentlyavailable reinforcing apparatuses therein. For example, the windshieldand side pillars on an automobile are typically curved and quite narrow.As a result, currently available reinforcing products generally cannotbe passed into the curved, narrow member in the manner necessary toachieve evenly distributed reinforcement along the length of the member.Thus, in order to properly reinforce these pillars, manufacturers mustprovide parts especially fabricated for a particular pillar. Thisrequires a high degree of manufacturing tolerance and does not allow asingle part to be used for a wide variety of hollow structural members.

There is a need for a lightweight, high-strength reinforcing productwhich is sufficiently versatile to be readily inserted into a wide arrayof small or irregularly-shaped channels.

SUMMARY OF THE INVENTION

The instant invention overcomes these problems by providing a thermallyexpansible reinforcer for reinforcing a hollow structural member (suchas an automobile rail) having a small and/or irregularly shaped cavity.

In more detail, the reinforcing member includes a plurality of pivotallyconnected sections (such as ball-and-socket connections) with eachsection comprising a support and a thermally expansible materialattached thereto. The support is preferably formed of nylon or metal andeach support can be shaped as a tubular, box-like structure which can beused in wide array of cavities. Alternately, one or more of the supportscan have a special shape (e.g., pyramidal) to allow the reinforcer toreadily enter particularly tight areas.

The reinforcing material is preferably a synthetic, resin-based materialwhich expands when subjected to temperatures achieved at specific pointsin a manufacturing process (e.g., such as during the paint or powderbake stages of automobile manufacturing processes). This expansion isachieved either by internally created thermal energy or by the externalapplication of heat to activate the material. As used herein, the term“thermally expansible” means both internally created thermal energy andthe external application of heat to expand and foam the reinforcingmaterial. The expansion temperature of the material should be at leastabout 300° F.

The inventive reinforcers are particularly useful in that their pivotalconnections allow them to be easily fed lengthwise into the opening of astructural member. Furthermore, by utilizing a reinforcer having anumber of interconnected sections, reinforcement of the structuralmember is uniformly distributed over the length of the member.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a reinforcer according to the invention;

FIG. 2 is a top view of a reinforcer of the invention having sleeves ofexpansible material around box-like supports;

FIG. 3 is a partial cutaway view depicting a ball-and-socket connection;

FIG. 4 is a partial cutaway view depicting a ball-and-socket connection;

FIG. 5 is a perspective view of an alternate embodiment of the inventionwherein one of the reinforcer supports is pyramidal in shape;

FIG. 6 is a perspective view of an alternate embodiment of the inventiondepicting the use of strips of expansible material on the reinforcersupports;

FIG. 7 is a perspective view of an alternate embodiment of the inventiondepicting the use of blocks of expansible material on the corners of thereinforcer supports;

FIG. 8 is a cross-sectional view of a support similar to those of FIG.5, depicting the use of a baffle material within the support;

FIG. 9 is a perspective view of an alternate shape for the reinforcersupports;

FIG. 10 is a perspective view of an automobile having structural membersreinforced with the inventive reinforcers prior to thermal expansion;

FIG. 11 depicts a structural member reinforced according to theinvention after thermal expansion has taken place;

FIG. 12 depicts the use of a bend tab for securing an expansiblematerial to a support of the inventive reinforcer;

FIG. 13 is a cross-sectional view taken along line 13—13 of FIG. 12;

FIG. 14 depicts the use of a push pin for securing an expansiblematerial to a support of the inventive reinforcer; and

FIG. 15 is a cross-sectional view taken along line 15—15 of FIG. 14.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Turning now to the figures, FIG. 1 illustrates a reinforcer 20comprising three rigid, box-like supports 22 a-c connected in atrain-like arrangement via pivotal connections 24 a,b.

Referring to FIG. 2, a reinforcer 26 is shown in more detail. Reinforcer26 comprises a chain of sections 28 a-c which each include respectivesupports 30 a-c. Each of supports 30 a-c comprises a tubular, box-likeconfiguration and includes respective outer surfaces 32 a-c. A quantityof an expansible synthetic resin material is attached to each outersurface 32 a-c so as to surround each support 30 a-c and form a sleeve34 a-c therearound. The sleeves 34 a-c are maintained on the supports 30a-c by way of a friction-fit.

Each support is similar in construction. That is, each of supports 30a-c comprises respective first ends 36 a-c, and second ends 38 a-cremote from first ends 36 a-c. A ball 40 a-c is attached, via a shaft 42a-c, to each support 30 a-c adjacent the first end 36 a-c thereofFurthermore, a socket 44 a-c is attached, via a shaft 46 a-c, to each ofsupport 30 a-c adjacent the second end 38 a-c thereof. Finally, each ofsockets 44 a-c comprises an outer surface 48 a-c having one or moreblocks 50 of expansible synthetic resin material attached thereto.

It will be appreciated that the use of ball 40 a-c and socket 44 a-callows for a pivotal ball-and-socket connection 52 a,b to be formedbetween each pair of sections 28 a-c. This connection is best seen inFIGS. 3 and 4 where a support 54 comprising a socket 56 having anopening 58 formed therein. A support 60 comprises a ball 62 disposed inthe opening 58 to allow free movement between supports 54 and 60 whilemaintaining a connection between these supports.

Although FIGS. 1-4 depict the inventive reinforcers as box-like supportshaving sleeves of expansible synthetic resin material attached thereto,it will be appreciated that a number of configurations can be used,depending upon the structural member to be reinforced. For example, FIG.5 depicts a reinforcer 64 comprising a first section 66 and second andthird sections 68 a,b. First section 66 comprises a pyramidal-shapedsupport 70 having five corner sections 72 (with only four sections 72being visible in FIG. 5), with a block 74 of expansible synthetic resinmaterial attached to each corner section 72. Finally, first section 66comprises a socket 76 having a block 78 of expansible synthetic resinmaterial attached thereto. Advantageously, the use of a pyramidal-shapedsupport 70 allows the reinforcer 64 to fit in small, hard-to-accesscorners or crevices of a structural member.

Second and third sections 68 a,b to one another are similar to oneanother in construction and include respective supports 80 a,b. Each ofsupports 80 a,b comprises a tubular, box-like configuration and includesrespective outer surfaces 82 a,b having recessed areas 84 a-d formedtherein. Each of recessed areas 84 a-d has a band 86 of expansiblesynthetic resin material deposited therein. Placing the bands 86 withinthe recessed areas 84 a-d serves to “lock” the bands 86 in place, thuspreventing movement thereof along the length of the supports 80 a,b.

Each of supports 80 a,b comprises respective first ends 88 a,b, andsecond ends 90 a,b remote from first ends 88 a,b. A ball (not shown) isattached to each support 80 a,b adjacent the first end 88 a,b thereof,while a socket 92 a,b is attached to each of supports 80 a,b adjacentthe second end 90 a,b thereof. Furthermore, each of sockets 92 a,bcomprises one or more blocks 94 of expansible synthetic resin materialattached thereto. Finally, each of sections 66 and 68 a,b are connectedin a train-like arrangement via ball-and-socket pivotal connections 96a,b similar to those described with respect to FIG. 2.

FIGS. 6 and 7 show alternate arrangements of the expansible syntheticresin material on the supports of the inventive reinforcers. Thesupports illustrated in FIGS. 6 and 7 are similar to those depicted inFIG. 2, with like numbering representing like parts. In FIG. 6, aplurality of strips 98 formed of the expansible synthetic resin materialare attached (e.g., such as by an adhesive) adjacent first ends 36 a,band second ends 38 a,b, on opposing sides of the supports 30 a,b.

The supports 28 a,b of FIG. 7 each include eight corner sections 100(with only six corner sections 100 of each support 28 a,b being visiblein FIG. 7). Blocks 102 of expansible synthetic resin material aresecured to respective corners 100. It will be appreciated that the widearray of configurations possible for attaching expansible syntheticresin materials to the supports of the inventive reinforcers allows theuser to adapt the reinforcer for a large number of structural membershaving channels or cavities of various shapes and sizes.

FIG. 8 is a cross-sectional view of a section of a reinforcer accordingto the invention similar to second or third sections 68 a,b of FIG. 5,with like numbering representing like parts. In this embodiment, afurther block 104 of an expansible synthetic resin material is provided.The block 104 can be formed of a reinforcing material if furtherstructural reinforcement is desired, or block 104 can be formed of abaffle material to assist in lessening noises which typically passthrough hollow structural members. A particularly preferred bafflematerial is disclosed in U.S. patent application Ser. No. 09/407,820,incorporated by reference herein.

FIG. 9 depicts yet another support shape which is useful for fittinginto small and/or irregular shaped cavities. In this embodiment, thesupport 106 is wedge-shaped and comprises an upper end 108 and a lowerend 110 as well as edges 112 a-c. Support 106 includes a ball 114adjacent lower end 110. Thus, the support 106 can be pivotally connectedvia ball 114 to a socket of another support as discussed with previousembodiments.

Each of the above-described supports, balls, sockets, and shafts shouldbe formed of a material having a melting point higher than the expansionor foaming temperature of the expansible material. Furthermore, themelting point of these items should be higher than any intermediateprocessing temperatures to which the intended structural member will besubjected. Preferred such materials include metal and nylon.

The expansible synthetic resin reinforcing material used in the presentinvention is preferably a dry, initially non-tacky material thatdevelops adhesion upon expansion so that it adheres to the surroundingstructural members when activated. Activation may be by heating, such asthat which occurs in automobile assembly plants. When subjected to atemperature of at least about 300° F., the thermally expansible foamingmaterial should have a percent expansion of at least about 40%,preferably at least about 125%, and more preferably from about 150-300%,to provide sufficient structural reinforcement and compressive strength.As used herein, the percent expansion is defined as:

100×{[(the specific gravity of the material before heating)−(thespecific gravity of the material after heating)]/(the specific gravityof the material after heating)}.

One preferred composition for use as the reinforcing material iscommercialized under the name SikaReinforcer (Sika Corporation, MadisonHeights, Mich.). In more detail, the most preferred compositioncomprises: from about 20-30% by weight of a styrene-butadiene-styrene(SBS) block co-polymer (e.g., Fina Clear 530®); from about 5-20% byweight of a polystyrene (e.g., Fina Crystal 500® and Fina Crystal 535®);from about 30-45% by weight of a bisphenol A-based liquid epoxy resin(e.g. Araldite 6010® and Epon 71®); from about 0.5-5% by weight of apigment such as carbon black; up to about 5% by weight butadieneacrylonitrile rubber (e.g., Nipol 1411); from about 1-10% by weighthydrated amorphous silica (e.g., HiSil 233); from about 10-20% by weightglass microspheres (e.g., Scotchlite S60); from about 0.1-5% by weightof a blowing agent such as azodicarbonamide (e.g., Celogen AZ 765®,Celogen AZ 754A®, and Celogen AZ 130®); from about 0.1-5% by weight of acatalyst such as N,N,-dimethyl phenyl urea (e.g., U405); from about0.1-5% by weight of a curing agent such as dicyandiamide (e.g., DDA10);and up to about 5% by weight of a “kicker” such as zinc oxide to lowerthe blowing temperature, with all percents by weight being based uponthe total weight of the composition taken as 100% by weight.

A particularly preferred composition for use as the reinforcing materialcomprises about 12.94% by weight polystyrene, about 23.22% by weight SBSblock copolymer, about 0.57% by weight carbon black, about 1.90% byweight butadiene acrylonitrile rubber, about 4.28% by weight hydratedamorphous silica, about 38.07% by weight bisphenol A-based liquid epoxyresin, about 14.75% by weight glass microspheres, about 0.46% by weightzinc oxide, about 2.85% by weight dicyandiamide, about 0.38% by weightN,N dimethyl phenyl urea, and about 0.57% by weight azodicarbonamide. Incertain applications where increased compressive strength and reducedfoaming and expansion are desired, the foregoing may be adjusted so thatthe polystyrene is reduced to about 12.63% by weight, the SBS blockcopolymer is reduced to about 22.59% by weight, and the butadieneacrylonitrile rubber is increased to about 2.85% by weight.

The composition are preferably formed by mixing the SBS block co-polymerwith a small portion (about {fraction (1/40)}th of the total amount) ofthe bisphenol A-based liquid epoxy resin in a heated mixer until thetemperature of the mixer reaches from about 240-260° F. (the temperatureof the mixture within the mixer is at least about 175° F.), and themixture is substantially homogeneous, at which time the polystyrene isadded to the mixer and mixing is continued. After the polystyrene issubstantially mixed with the SBS block co-polymer/epoxy resin mixture,the remainder of the bisphenol A-based epoxy resin is slowly added tothe mixer, stopping and starting the mixer as necessary, with theingredients being thoroughly mixed to obtain a substantially homogeneousmixture. The desired amount of this mixture is placed in a heated mixer(set at a temperature of about 250° F.) and mixing is commenced. Whilemixing, the carbon black and rubber are added to the mixer and mixing isstopped once a homogeneous mixture is obtained within the mixer. Eitherthe silica or glass microspheres is added to the mixer, and mixing isresumed and continued until the mixture is homogeneous. This step isrepeated, adding the other of the silica or glass microspheres.

The temperature of the mixer is then set to a temperature below 160° F.,the blowing agent(s), catalyst(s), kicker, and curing agent(s) areadded, and mixing is resumed and continued only until the mixture ishomogeneous. The resulting mixture is then preferably extruded intostrands (at an extruder temperature of 170-180° F. and screw rotationspeeds of about 400 rpm) and cut into pellets. The resulting pellets areinjection molded at a temperature of about 180-200° F. using injectionmolding equipment designed to form the desired shape of the reinforcingmaterial to be attached to the supports.

In application, the reinforcer is preferably provided to a manufacturerpreassembled (i.e., with the non-expanded synthetic resin materialattached to the particular supports) for insertion lengthwise into thecavity of the desired structural member, such as during the constructionof an automobile. That is, the number, shape, and size of the supportsare selected according to the particular pillar or other structuralmember in which the reinforcer will be used. However, unlike prior artreinforcing products, the inventive reinforcer is adaptable to manydifferent structural members of many different vehicles due to thepivotal interconnections between the individual supports.

Referring to FIG. 10, a car 116 is depicted as having a windshieldpillar 118, an upper rail 120, a B pillar 122, and a bottom rail 124,each of which is generally hollow and requires structural reinforcement,particularly for the safety of the car occupants during a side-impactcollision. Windshield pillar 118 comprises a cavity 126 having areinforcer 128 disposed therein. This particular reinforcer 128comprises two pivotally linked sections 130 a,b having sleeves of anexpansible synthetic resin material similar to the embodiment shown inFIG. 2. Upper rail 120 and B pillar 122 comprise respective cavities132,134 having respective reinforcers 136,138 disposed therein. Each ofreinforcers 136,138 comprise bands of expansible synthetic resinmaterial similar to the arrangement described with respect to theembodiment of FIG. 5.

Finally, bottom rail 124 comprises a cavity 140 having a 4-sectionreinforcer 142 disposed therein. The sections 144 a-d include opposingstrips of an expansible synthetic resin reinforcing material attachedthereto similar to the arrangement shown in FIG. 6.

It will be appreciated that each of cavities 126, 132, 134, 140 (andparticularly cavities 126, 132, 134) are narrow and quite difficult toreinforce successfully. That is, it has typically been required to placemetal bars fabricated specifically for that particular structural memberof that particular vehicle. This requires a high degree of manufacturingtolerance and adds undesirable additional weight to the vehicle.Alternately, if prior art foamable reinforcing products are utilized, ithas been necessary to add individual units at multiple locations withinthe pillar. This is quite time-consuming and does not generally provideuniform and reliable reinforcement of the structural member. However, asshown in FIG. 10, the inventive reinforcer can simply be fed lengthwiseinto a narrow, irregularly shaped cavity and temporarily secured at asingle location near the cavity opening. Due to the pivotal connectionsbetween the various sections of the inventive reinforcer, the sectionsare able to twist and turn as necessary to navigate the structuralmember cavity.

After the reinforcer is placed in the cavity of the structural member,the vehicle can be subjected to a number of process or manufacturingsteps which are typically carried out on the vehicle body withoutaffecting the ability of the synthetic resin reinforcing material toexpand when exposed to the actual activating temperature. When thistemperature is reached (e.g., such as during the paint bake stage), thesynthetic resin material begins to expand in all directions towards thewalls forming the cavity (see FIG. 11) so as to substantially fill thecavity. Furthermore, the material on the outer surface of the socketsalso expands around the pivotal connection, thus essentially orsubstantially immobilizing the connections to form high-strength, rigid,reinforcement within the structural member.

The expanded synthetic resin material preferably has a compressivestrength (using a sample having a diameter of 2 inches and a length of 4inches and a compression rate of 0.5 inches/minute) of at least about1200 psi, preferably at least about 1400 psi, and more preferably atleast about 1600 psi. Prior to expansion, the material has a specificgravity (with reference to water) of at least about 0.90, while thespecific gravity (with reference to water) of the expanded material 60is less than about 0.47, preferably less than about 0.37, and morepreferably less than about 0.32. The expanded material has a ratio ofcompressive strength:specific gravity after bake of at least about2500:1, preferably at least about 3000:1, and more preferably at leastabout 3600:1.

Although the present invention has been described with reference to thepreferred embodiments illustrated in the accompanying figures, it isnoted that substitutions may be made and equivalents employed withoutdeparting from the scope of the invention. For example, although thepreferred embodiment is illustrated in connection with a structuralmember of a motor vehicle, the inventive reinforcing members may beemployed in other structural members as well (e.g., in a boat, in anairplane, etc.). Furthermore, while SikaReinforcer is cited as onepreferred composition of which the expansible synthetic resin materialcan be formed, any material meeting the above-described strength andexpansion properties is suitable.

Also, while adhesive strips, friction-fits, and recessed areas are usedto retain the expansible material on the supports in the aboveembodiments, other fasteners can be used as well. For example, FIGS. 12and 13 depict a support wall 146 having a block 148 of expansiblesynthetic resin material supported thereon. Specifically, the block 148has an opening 150 through which a bend tab 152 passes so as to retainblock 148 in place until thermal expansion thereof FIGS. 14 and 15illustrate yet another fastener wherein a support wall 154 has a block156 of an expansible synthetic resin material attached thereto. In thisembodiment, a push pin 158 is passed through an opening 160 on the wall154 and into the block 156 so as to hold it in place.

While the reinforcers according to the invention have been described asa plurality of pivotally connected sections, it will be appreciated thatthis includes a single piece that is capable of being fed into andthrough small and/or irregular cavities. Finally, while the illustratedembodiments depict the inventive reinforcer as a plurality of supportsin a train-like configuration (i.e., unbranched), it is also possible toarrange the supports in a branched manner if desired.

I claim:
 1. A method of reinforcing a structural member presenting anelongated, nonlinear passageway communicating with an access opening,said method comprising the step of inserting an elongated, flexiblereinforcer lengthwise through the access opening so that the reinforcertravels along said passageway, said reinforcer comprising at least twosupports and respective pieces of an expansible synthetic resin materialcoupled to each of said supports, said supports being pivotallyconnected to one another.
 2. The method of claim 1, wherein saidpassageway comprises a first end adjacent said access opening, a secondend remote from said access opening, and a point about halfway betweensaid first and second ends, said reinforcer traveling to at least aboutsaid halfway point.
 3. The method of claim 1, wherein said structuralmember is a rail of a motor vehicle.
 4. The method of claim 1, whereinsaid structural member is a frame of a motor vehicle.
 5. The method ofclaim 1, further including the step of heating said reinforcer so as tocause said synthetic resin material pieces to expand, said reinforcerbeing substantially inflexible after said expansion.
 6. The method ofclaim 1, wherein said structural member is a rail of a motor vehicle. 7.The method of claim 1, wherein said structural member is a frame of amotor vehicle.
 8. The method of claim 1, further including the step ofheating said reinforcer so as to cause said synthetic resin material toexpand, said sections being essentially immobilized after saidexpansion.
 9. A method of reinforcing a structural member defining acavity, said method comprising the step of positioning a reinforcer insaid cavity, said reinforcer comprising sections having respective axesand comprising respective pieces of an expansible synthetic resinmaterial coupled to of each said sections, said reinforcer beingconfigured so that at least two of said sections are shiftable between aparallel axes position and a nonparallel axes position as necessaryduring said positioning step, said sections being pivotally connected toone another.